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ATLASGAL-selected massive clumps in the inner Galaxy VI. Kinetic temperature and spatial density measured with formaldehyde
Tang, X. D.1,2,3; Henkel, C.1,4; Wyrowski, F.1; Giannetti, A.1,5,6; Menten, K. M.1; Csengeri, T.1; Leurini, S.1,7; Urquhart, J. S.1,8; Koenig, C.1; Guesten, R.1; Lin, Y. X.1; Zheng, X. W.9; Esimbek, J.2,3; Zhou, J. J.2,3
2018-03-15
Source PublicationASTRONOMY & ASTROPHYSICS
ISSN1432-0746
Volume611Pages:17
Corresponding AuthorTang, X. D.(xdtang@mpifr-bonn.mpg.de)
AbstractContext. Formaldehyde (H2CO) is a reliable tracer to accurately measure the physical parameters of dense gas in star-forming regions. Aims. We aim to determine directly the kinetic temperature and spatial density with formaldehyde for the similar to 100 brightest ATLASGAL-selected clumps (the TOP100 sample) at 870 mu m representing various evolutionary stages of high-mass star formation. Methods. Ten transitions (J = 3-2 and 4-3) of ortho-and para-H2CO near 211, 218, 225, and 291 GHz were observed with the Atacama Pathfinder EXperiment (APEX) 12 m telescope. Results. Using non-LTE models with RADEX, we derived the gas kinetic temperature and spatial density with the measured para-H2CO 3(21)-2(20)/3(03)-2(02), 4(22)-3(21)/4(04)-3(03), and 4(04)-3(03)/3(03)-2(02) ratios. The gas kinetic temperatures derived from the para-H2CO 3(21)-2(20)/3(03)-2(02) and 4(22)-3(21)/4(04)-3(03) line ratios are high, ranging from 43 to >300 K with an unweighted average of 91 +/- 4 K. Deduced T-kin values from the J = 3-2 and 4-3 transitions are similar. Spatial densities of the gas derived from the para-H2CO 4(04)-3(03)/3(03)-2(02) line ratios yield 0.6-8.3 x 10(6) cm(-3) with an unweighted average of 1.5 (+/- 0.1) x 10(6) cm(-3). A comparison of kinetic temperatures derived from para-H2CO, NH3, and dust emission indicates that para-H2CO traces a distinctly higher temperature than the NH3 (2, 2)/(1, 1) transitions and the dust, tracing heated gas more directly associated with the star formation process. The H2CO line widths are found to be correlated with bolometric luminosity and increase with the evolutionary stage of the clumps, which suggests that higher luminosities tend to be associated with a more turbulent molecular medium. It seems that the spatial densities measured with H2CO do not vary significantly with the evolutionary stage of the clumps. However, averaged gas kinetic temperatures derived from H2CO increase with time through the evolution of the clumps. The high temperature of the gas traced by H2CO may be mainly caused by radiation from embedded young massive stars and the interaction of outflows with the ambient medium. For L-bol/M-clump greater than or similar to 10 L-circle dot/M-circle dot, we find a rough correlation between gas kinetic temperature and this ratio, which is indicative of the evolutionary stage of the individual clumps. The strong relationship between H2CO line luminosities and clump masses is apparently linear during the late evolutionary stages of the clumps, indicating that L-H2CO does reliably trace the mass of warm dense molecular gas. In our massive clumps H2CO line luminosities are approximately linearly correlated with bolometric luminosities over about four orders of magnitude in L-bol, which suggests that the mass of dense molecular gas traced by the H2CO line luminosity is well correlated with star formation.
Keywordstars: formation stars: massive ISM: clouds ISM: molecules ISM: abundances radio lines: ISM
DOI10.1051/0004-6361/201732168
WOS KeywordSTAR-FORMING REGIONS ; YOUNG STELLAR OBJECTS ; MOLECULAR CLOUDS ; GALACTIC-CENTER ; PHYSICAL-PROPERTIES ; COMPLETE SAMPLE ; INFALL MOTIONS ; CEPHEUS CLOUDS ; SURVEY AMMONIA ; IRAS SOURCES
Indexed BySCI
Language英语
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000427914900001
PublisherEDP SCIENCES S A
Citation statistics
Cited Times:3[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://libir.pmo.ac.cn/handle/332002/22392
Collection中国科学院紫金山天文台
Corresponding AuthorTang, X. D.
Affiliation1.Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany
2.Chinese Acad Sci, Xinjiang Astron Observ, Urumqi 830011, Peoples R China
3.Chinese Acad Sci, Key Lab Radio Astron, Urumqi 830011, Peoples R China
4.King Abdulaziz Univ, Astron Dept, POB 80203, Jeddah 21589, Saudi Arabia
5.INAF Ist Radioastron, Via P Gobetti 101, I-40129 Bologna, Italy
6.Italian ALMA Reg Ctr, Via P Gobetti 101, I-40129 Bologna, Italy
7.INAF Osservatorio Astron Cagliari, Via Sci 5, I-09047 Selargius, CA, Italy
8.Univ Kent, Sch Phys Sci, Ingram Bldg, Canterbury CT2 7NH, Kent, England
9.Nanjing Univ, Sch Astron & Space Sci, Nanjing 210093, Jiangsu, Peoples R China
Recommended Citation
GB/T 7714
Tang, X. D.,Henkel, C.,Wyrowski, F.,et al. ATLASGAL-selected massive clumps in the inner Galaxy VI. Kinetic temperature and spatial density measured with formaldehyde[J]. ASTRONOMY & ASTROPHYSICS,2018,611:17.
APA Tang, X. D..,Henkel, C..,Wyrowski, F..,Giannetti, A..,Menten, K. M..,...&Zhou, J. J..(2018).ATLASGAL-selected massive clumps in the inner Galaxy VI. Kinetic temperature and spatial density measured with formaldehyde.ASTRONOMY & ASTROPHYSICS,611,17.
MLA Tang, X. D.,et al."ATLASGAL-selected massive clumps in the inner Galaxy VI. Kinetic temperature and spatial density measured with formaldehyde".ASTRONOMY & ASTROPHYSICS 611(2018):17.
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